Rex is an AI service that runs order-to-cash and accounts receivable operations for enterprises. Founders Merlin Kafka and Lewis Blackwood spent 4 years at an a16z-backed startup helping finance teams at startups like Cognition, Legora and Bridge automate revenue collection. The problem is 100x bigger in the enterprise, so they built Rex: agents that do the work end-to-end. Live in production with Synthesia.

https://www.youtube.com/watch?v=BKS7qaZS8Is

Revenue ≠ cash

Enterprises invoice customers, then spend months chasing the money through email chains, PDFs and ancient web portals. A $1M invoice sits unpaid because one PO number didn't match.

Multiply that across thousands of customers and you get 100+ person teams, often offshore, doing this by hand: collections, invoice submission, dispute resolution, deduction management, cash application. Order-to-cash is the most outsourced process in finance because the work needs judgment. Reading a customer's email and deciding whether their dispute is valid. Working out which of 14 open invoices a lump-sum payment covers. Knowing that this account always pays late but always pays, and that one needs escalating now.

AR automation software has existed for 20 years and the teams never got smaller, because the tools organise the work while people still do it. Businesses invoice each other tens of trillions of dollars a year; the labour and outsourcing spend on collecting it is over $100B. Until now the only way to scale was headcount or a BPO contract.

What Rex does

Rex connects to the ERP (NetSuite, SAP, Oracle), CRM (Salesforce), billing system and shared AR inbox, and learns how the team runs the process today. That knowledge becomes editable agent operating procedures: how to chase a Fortune 500 buyer vs a startup, which deductions get investigated vs written off, when a dispute goes to a human.

Then agents run those procedures across thousands of accounts in parallel:

• Collections and payment follow-ups, including the long tail no team gets to
• Invoice submission and status tracking inside procurement portals (SAP Ariba, Coupa, Tungsten and hundreds of others)
• Dispute and deduction investigation
• Remittance processing and cash application
• Responding to customer finance emails
• Updating ERP, CRM and billing records
• Routing exceptions to the team for approval

Portals deserve a special mention: an increasing share of enterprise invoices must be submitted and tracked inside the buyer's procurement system. It's the work AR teams hate most and the work software vendors ignore. Rex treats it as core.

Is Rex a managed service or software?

Enterprises can partner with Rex as a managed service provider or let their team operate Rex. AR software (dunning tools, collections worklists, AR dashboards) organises work for a team to do. Rex agents do the work, and the finance team approves exceptions. With Rex, the team stops drowning in routine chasing and handles the judgment calls. Customers compare Rex to their next AR hire, their offshore team, or their BPO contract.

Can finance teams trust AI agents with collections?

Autonomy is earned, not switched on. Each procedure starts supervised: Rex proposes, the team approves. Once a procedure hits its accuracy bar for the account, it graduates and runs autonomously. Safe, high-volume work goes first; judgment-heavy edges stay gated as long as the team wants. Every action is logged with its full reasoning, so finance audits the system instead of babysitting it.

Traction

Rex is live in production with enterprises like Synthesia, running collections, portal submissions, inbox triage and cash application. Cases that used to take weeks of back and forth resolve in minutes.

Get in touch

If invoice volume is outgrowing the finance team, or order-to-cash runs on offshore headcount or a BPO contract, get in touch: rex.inc